Core Connections Geometry, 2013
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Core Connections Geometry, 2013 View details
Chapter Closure

Exercise 119 Page 205

a To find the perimeter of a figure, we need to add all of its sides. In this case, we have a right triangle which means we can find the unknown hypotenuse by using the Pythagorean Theorem.
a^2+b^2=c^2
5^2+ 12^2=c^2
Solve for c
25+144=c^2
169=c^2
c^2=169
c=± 13

c > 0

c=13
When we know the last side of the triangle, we can find the perimeter by adding all of the sides.

Perimeter: 5+12+13=30 The area of a triangle is the product of the base and height divided by 2. In a right triangle, these dimensions are made up by the triangle's legs.

Knowing the height and base of the triangle, we can calculate the area.
A=1/2bh
A=1/2( 5)( 12)
Simplify right-hand side
A=1/2* 60
A=60/2
A=30
b To determine the perimeter, we have to find the length of the unknown sides. By adding a few dashed segments to the diagram, these are easier to identify.
Having identified all of the sides, we can calculate the perimeter by adding them.

Perimeter: 2+7+4+2+4+6+6+3=34 To find the area, we will keep some of the information about the unknown lengths we calculated when determining the perimeter. By dividing the figure into two rectangles and a square, we can calculate the area of these shapes and then add them.

Now we can calculate the total area of the shape. Area: (2)(3)+ (4)(4)+ (4)(6)=46

c To calculate the perimeter, we will first divide the polygon into a rectangle and a right triangle.
Since we know the right triangle's legs, we can calculate the hypotenuse by using the Pythagorean Theorem.
a^2+b^2=c^2
4^2+ 3^2=c^2
Solve for c
16+9=c^2
25=c^2
c^2=25
c=± 5

c > 0

c=5
Let's add the final side to the diagram.

Having identified all of the sides, we can calculate the perimeter by adding them. Perimeter: 4+7+5+10=26 The area can be determined as the sum of the triangle and rectangle that was identified when finding the perimeter. Area: (4)(7)+1/2(4)(3)=34